Magnetic anisotropy in Fe-based ferromagnetic materials

Fe-based magnetic materials are widely applied in technologies and industries, with most of the applications for soft magnetic materials, because of the low magnetocrystalline anisotropy (MCA) of bcc Fe. However, it is possible to realize magnetic hardening in Fe-based materials as we have learned from the early carbon steel permanent magnets, although the coercivity of the magnets was modest. Recent efforts to search for rare-earth-free hard magnetic materials have shown more promising evidences for achieving high MCA in Fe-based materials. In this presentation, we discuss recent developments of Fe-based hard and semi-hard magnetic materials with a focus on mechanisms of high MCA in alloys and intermetallic systems with Fe as the major content. We have identified the structures and the magnetic properties of the Fe-based binary or ternary systems containing p-block and d-block elements with considerable MCA. Furthermore, it is also important to know and to understand that the MCA in Fe-based magnetic materials can be tailored/enhanced through chemical and/or structural modifications that will lead to “artificially engineered” hard and semi-hard magnetic materials for advanced permanent magnets in the future. Experimental results on the Fe-rich carbide nanoparticles and nanorods with different aspect ratio will be discussed as an example of the materials investigated.